When to start OPKs?

Hey ladies!

I just took my last clomid pill yesterday first round (cycle days 3-7). I really don’t have a set cycle as this is my first time taking clomid and my periods were extremely irregular previously. When do you ladies recommend starting the OPKs as i really don’t want to miss it! And also I read different things about using first morning urine and waiting until after 10am to test. What are your thoughts about when to start and what time of day is best?